Walking beam track tension device

ABSTRACT

The invention is a walking beam for a tandem wheel set having a continuousrack wrapped around tires on the set. The set&#39;s wheels are mounted on shoes which slide on bars forward or backward relative to the vehicle having the wheel set. A carriage member is linked to the shoes such that translation of the carriage member moves the shoes together or apart. Translation of the carriage member is effected by a rod rotatably mounted to the walking beam and threadingly engaged with the carriage member. Moving the shoes together reduces tension on the track whereas moving the shoes apart increases tension the track.

GOVERNMENT USE

The invention described herein may be manufactured, used and licensed byor for the U.S. Government for governmental purposes without payment tome of any royalty.

BACKGROUND

Military trucks and trailers typically travel over both roads andterrain, and these vehicles have wheel mounting suspension systemsdesigned to operate on various ground surfaces. One such suspensionsystem component is a walking beam rotatably mounted at its center oneither end of a vehicle axle, the walking beam having a forward arm, arearward arm telescoped thereon and one or more wheels mounted on eacharm. Each arm commonly has a pair of wheels coaxially mounted thereto,with one wheel on the inboard side of the arm and the other wheel on theoutboard side of the arm. Conventionally a track wraps about the foreand aft wheels on the walking beam to enhance the vehicle's ability totraverse rough terrain. These tracks need to be properly tensioned toenable the vehicle to travel over a paved road at normal roadway speedsand the relative telescoped position of the rearward arm can be changedto adjust tension on the track. However, known tension adjustingmechanisms, as shown in FIG. 8, are typically difficult to use,especially when the track is wrapped around the vehicle's wheels.

SUMMARY OF THE INVENTION

I address the above problem by providing a walking beam having an easilyaccessible track tensioning mechanism that is easy and quick to use. Mywalking beam has an axle engagement collar fixed between forward andrearward arms upon which ride shoes where wheels are mounted. The shoesare linked to a carriage member that translates on guides fixed relativeto the collar, and carriage member translation adjusts the distancebetween the fore and aft wheels. The carriage member threads with arotatable rod axially fixed relative to the collar and rotating the rodeffects effects translation the carriage member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing my walking beam incorporated in atandem wheel set with a continuous track or tread wrapped around tiresof the set, two wheels of the set being removed to permit a better viewof the walking beam. FIG. 2 is a perspective view of my walking beamwith one of the retainer plates removed to show the walking beam'scarriage member and nearby structure.

FIG. 3 is a partial sectional view showing a shoe on the end of arectangular bar of the walking beam.

FIG. 4 is a perspective view of links of the walking beam.

FIG. 5 is a perspective view of a subassembly of the walking beamcomprised of a collar, a mid block integral with the collar and therectangular bars.

FIG. 6 is a plan view of the carriage member.

FIG. 7 is a perspective view of the retainer plates.

FIG. 8 is a prior art walking beam assembly.

PRIOR ART

FIG. 8 shows a prior art walking beam assembly 210 having telescopingarms 212 and 214. Internally threaded blocks 218 and 220 fixed torespective arms are engaged by an adjustment screw 216. Turning screw216 axially extends or retracts arm 212 with respect to arm 214 tolengthen or shorten the walking beam assembly.

DETAILED DESCRIPTION

FIG. 1 shows my walking beam 12 as part of a tracked tandem wheel system10, where the beam is pivotally connected in known fashion to vehicleaxle 14 by nut 16 on the axle's threaded stub shaft 18. At one end ofwalking beam 12 is rotatably mounted wheel 20 having tire 22 mountedthereon and at the other end of the beam is rotatably mounted wheel 24having tire 26 thereon. When system 10 is fully assembled, a thirdrotatable wheel having a third tire (neither shown) will be mounted tohub 28 and will be concentrically engaged with spindle 30. Similarly, afourth rotatable wheel having a fourth tire (neither shown) will bemounted to hub 32 and will be concentrically engaged with spindle 34.

System 10 includes a continuous, one-piece band of flexible track ortread 36, which tightly wraps around the tires so that the tires andwheels rotate in concert the rolling of the track. On the innerperipheral surface of track 36 is a crenellated center guide 38 havingblock-like guide elements 40 aligned along a fore-to-aft axis of thetrack. As the track rolls, guide elements 40 pass between a first pairof tires--tire 22 and the third tire, and will also pass between asecond pair of tires--tire 26 and the fourth tire. The paired tires trapcenter guide 38 therebetween so as to retain track 36 on wheel system10.

FIG. 2 is an enlarged view of walking beam 12 wherein retainer plate 42is removed from the walking beam so as to more clearly illustrate theinner components of the beam. Beam 12 has ribbed collar 44 fixed atop amid block 46 from which extend cross-sectionally rectangular elongatebars 48 and 50. The bars are either in axial alignment or formtherebetween an upper obtuse angle "A" (FIG. 5) of, say, 170 to 178degrees. Closely and slidably fitting on the ends of bars 48 and 50 areshoes 52 and 54, both shoes defining a blind cavity such as cavity 56(FIG. 3) to receive the end of a respective elongate bar. Shoe 52defines a one pair of tabs 53 and shoe 54 defines another pair of tabs55, each pair of tabs defining a flat, narrow gap therebetween.

Extending downward from mid block 46 in a general plane with bars 48 and50 is threaded rod 58, which rotates on rod axis 59 relative to block 46but does not translate relative to the block. Fixed to the end of rod 58opposite from block 46 is flat hexagonal head 60, and between the blockand head at least part of the rod is threaded. The threaded part of rod58 passes through and engages threaded aperture 61 (FIG. 6) of carriagemember 62 such that rotation of rod 58 relative to carriage member 62translates the carriage member along the rod.

Referring now to FIGS. 2 and 6, one end of carriage member 62 definesone pair of opposed bracket walls 64 and the other end of carriagemember 62 defines another pair of opposed bracket walls 66. Mutuallyfacing inner surfaces 68 of walls 64 and analogous inner wall surfaces70 of walls 66 are parallel to one another and define flat, narrow gaps.Each wall 64 defines an aperture 72 centered on axis 76 and each wall 66defines an aperture 74 centered on axis 78. Running from top to bottomof carriage member 62 and disposed along aperture 61 on opposite sidesof the carriage member 62 are cross-sectionally flat rectangular keyways80.

As seen in FIGS. 2 and 4, elongate link 82 connects tabs 53 to bracketwalls 64, one end of link 82 fitting bearingly but movably between tabs53 and the opposite end of link 82 fitting bearingly but movably betweenbracket walls 64. Likewise, elongate link 84 connects tabs 54 to bracketwalls 66, one end of link 84 fitting bearingly but movably between tabs55 and the opposite end of link 84 fitting bearingly but movably betweenbracket walls 66. Ends 82 and 84 are pivotally attached to therespective pairs of tabs or bracket walls by pivot pins 86 extendingthrough the pairs of the respective bracket walls or tabs.

Referring to FIGS. 2 and 7, retainer plates 42 and 43 are fixed toeither side of mid block 40 by bolts 88, by welding or by any othersuitable means. Fixed between plates 42 and 43 at their lower ends is alower terminus plate 90, the fixing means again being bolts, welding orany other suitable mechanism. Mid block 46, lower terminus plate 90 andretainer plates 42 and 43 together form a strong, rigid open-box framesurrounding and retaining carriage block 62.

Rod 58 passes through plate 90 but is not threaded therewith, so thatrod 58 rotates freely while remaining translationally fixed relative toplate 90. On opposed inner surfaces of the retainer plates are flat,rib-like guides 92 and 94 oriented parallel to rod axis 59. Keyways 80of carriage member 62 fit closely and slidably on guides 92 and 94 (FIG.7) so that the carriage member translates up and down along the guideswhen rod 58 turns.

One may create a torque on carriage member 62 in the general planedefined by links 82 and 84 and elongate bars 48 and 50. The torque wouldbe created by force components acting along links 82 and 84 when tandemwheel system 10 engages the ground. The torque will tend to tilt thecarriage member about lateral axis 96 (FIG. 6) passing through thevolumetric center of the carriage member normal to axis 59. Because ofthe torque, carriage member 62 will bind or rod 58 or on guides 92 and94 when system 10 engages the ground. The torque thus preventstranslation of the carriage member on rod 58 during operation of system10. The torque can be created by locating one axis pin 86 on carriagemember 62 assymetrically with respect to the other axis pin 86 on thecarriage member. That is, one axis pin either is further from axis 59 oropposes a different point on axis 59 than the other axis pin. Anotherway to create the aforementioned torque is to dispose links 82 and 84 atunequal angles with respect to axis 59.

One may in some applications prefer that rod 58 be threaded with plate90 and that rod 58 be axially fixed but rotatable with respect tocarriage member 62. In such applications, the portion of rod 58 betweencollar 44 and carriage member 62 would either be truncated or eliminatedaltogether, whereby rod will not limit upward translation of carriagemember 62 in FIG. 2. In this arrangement, head 60 moves away from track36 when the shoes slide away from collar 44 during tightening of track36 onto wheel system 10. Head 60 in this arrangement thus has lesstendency to interfere with the track during over-terrain travel thereof.

Referring to FIG. 1 and 2, removal of track 36 from tandem wheel system10 is accomplished by first turning rod 58 so that carriage member 62translates downward. Shoes 52 and 54 slide toward one another by virtueof their linked connection to the carriage member, whereby one set ofcoaxial tires is drawn toward the other set of coaxial tires. Track 36is now loose on the tires and can be removed from system 10. Installinga new track can be done by the reverse process.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described herein since obviousmodifications will occur to those skilled in the relevant arts withoutdeparting from the spirit and scope of the following claims.

I claim:
 1. A walking beam for a tandem wheel system allowing removal ofa continuous track wrapped around two or more sets of wheels,comprising:a collar rotatable upon the end of a vehicle axle; a midblock fixed to the collar; two elongate cross-sectionally rectangularbars fixed to the mid block, the bars extending in opposite directionsgenerally perpendicular to the axle; shoes slidable on the bars, theshoes defining rectangular openings closely receiving ends of the bars;means for mounting the sets of vehicle wheels on the shoes; a rodrotatably connected to the mid block, the rod being translationallyfixed relative to the mid block; a pair of retainer plates fixedlyconnected to the mid block, the retainer plates each having an innersurface faced toward the rod: a terminus plate fixed to ends of theretainer plates more remote from the collar, whereby the mid block,retainer plates and terminus plate form a rigid open-box frame, theterminus plate defining an aperture through which the rod extends andwith respect to which the rod freely rotates, the rod axially fixedrelative to the terminus plate; guides fixed inside the frame anddisposed along the rod; a carriage member slidable along the guides andthreadingly engaged to the rod, the carriage member defining keywaysclosely fit on the guides; two pairs of parallel bracket walls connectedto the carriage member, the bracket wall of each pair having opposedinner wall surfaces defining therebetween a flat, smooth, narrow bracketgap; a pair of tabs connected to each shoe, the pairs of tabs definingflat smooth tab gaps therebetween; a first link connected between thecarriage member and one of the shoes, the first link having first flatends closely but movably sandwiched respectively by the pair of tabs onthe one shoe and one pair of bracket walls on the carriage member; asecond link connected between the carriage member and another of theshoes, the link having second flat ends closely but movably sandwichedrespectively by the pair of tabs on the other shoe and another pair ofbracket walls on the carriage member.
 2. The walking beam of claim 1wherein the carriage member is subjected to a torque tending to tilt thecarriage member about an axis normal to the rod whereby the carriagemember binds with another element of the walking beam.
 3. The walkingbeam of claim 1 wherein the bars each defines an angle of greater than90 degrees with the rod.
 4. A walking beam for a tandem wheel system,comprising:a collar rotatable upon the end of a vehicle axle; two barsfixed relative to the collar; shoes connected to the bars, at least oneshoe slidable on one of the bars; means for mounting vehicle wheels onthe shoes; a guide connected to the walking beam fixed relative to thecollar; a carriage member connected to the guide; means to translate thecarriage member along the guide; a link pivotally connected with thecarriage member and the one shoe.
 5. The walking beam of claim 4 whereinthe carriage member is subjected to a torque tending to tilt thecarriage member in the general plane defined by the carriage member thelink and the bars, whereby the carriage member is inhibited fromtranslating along the rod.
 6. The walking beam of claim 4 wherein thebars each defines an angle of greater than 90 degrees with the rod.
 7. Awalking beam for a tandem wheel system, comprising:a collar rotatablyconnected to the end of a vehicle axle, the collar having a blockportion integral therewith; two bars fixed to the collar and extended inopposite directions from the collar; shoes slidable on the bars; a rodrotatably connected to the collar and translationally fixed relative tothe collar; a pair of retainer plates fixedly connected along the rod tothe collar; a guide connected to one of the retainer plates, the guidedisposed along the rod; a carriage member slidable along the guide andthreadingly engaged to the rod, whereby rotating the rod slides thecarriage member along the guides; a first link pivotally connected withthe carriage member and one of the shoes; a second link member connectedwith the carriage member and another of the shoes; the shoestranslatable an the bars in concert with translation of the carriagemember along the guides.
 8. The walking beam of claim 7 wherein thelinks tilt the carriage member relative to the carriages pathway alongthe guide and the rod, whereby the carriage member tends to bind withone or more other walking beam elements.
 9. The walking beam of claim 8wherein the other walking beam elements include the rod and the guide.10. The walking beam of claim 9 further comprising:two pairs of bracketwalls connected to the carriage members, the pairs of bracket walls eachdefining a flat, smooth bracket gap; a pair of tabs connected to each ofthe shoes, the pairs of tabs defining flat, smooth tab gaps; flat,smooth ends on either end of both links, wherein respective flat, smoothends of the links closely but movably fit in respective ones of thegaps; whereby the links tend to reinforce the bars.